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MK1 FAQ

MK1 Modifications:

What modifications are done?

The 3.3V power supply to the on-board clocks is

separated, isolated &

then supplied from an external battery. By doing this the power to the clocks is very low noise.. The on-board 3.3V regulator is removed & this power is now supplied from another external 3.3V battery. This powers the clock handling output stages of the CPLD chip.

Is the modified Hiface now separate from the computer's power supply?

No, the 5V from the computer is still used by the Hiface to power the SPDIF generating chip. The 5V is also as the input to an on-board 1.8V regulator. The 1.8V powers the CPLD also. The 5V power form the computer is fed through the USB cable.

Is there no longer a need for the 5V power over USB?

Yes, there is still a need for this USB 5V supply as it is used to power the less critical areas of the device.

Batteries:

What batteries are being used?

These are Lithium Nano Phosphate (LiFePO4) batteries. This is a new & safer formulation of Lithium battery technology. It has nearly the same power to weight ratio as lithium batteries but doesn't have any of the safety issues or fire hazards associated with Lithium Ion batteries.

How long do the batteries last before needing replacement?

A longevity of 15 years is given by the manufacturer, A123, for high current usage such as power tools or electric vehicles. Our low current use should ensure an even longer lifetime.

How long do the batteries last before needing a re-charge?

A charge should last for 8 hours BUT the batteries are only being used when the unit is turned on. One battery runs the clocks & one battery runs a chip. The one that runs the chip will drain in about 8 hours (maybe shorter), the one that runs the clocks in about 3 days. BUT when you turn off the unit, the batteries equalise so the drained battery will be recharged by the un-drained one in about 10-15 mins & you are good to go again. I haven't tested the timing of this but I've been told by users that they get days from their fully charged batteries if operated in this way.

Do these batteries need a special handling/charging regimen like other batteries?

No, these batteries do not suffer from memory effects like others & don't need to be drained fully & then re-charged. They can be used straight away without any special consideration.

Will they explode or catch fire if I overcharge them?

No, but they will die like all batteries! I had a user who unknowingly was using a 2 battery charger putting out 7.2V to charge them (my 2 batteries are in parallel & so only need a max 3.6V charge). The batteries survived for a while before finally dying. They didn't catch fire or emit any noxious fumes - simply overheated & died. On examination one battery endcap had partially come off the end of the battery (it still measured 3.2V).

Will it damage the batteries if I deeply deplete them?

No, but it's not a recommended practise. The manufacturers recommend that they are not deeply depleted (<2.7V) in high current situations as this effects their longevity. In our low current usage this is less of a worry, possibly not a worry at all but I still recommend not to leave them on continuously for days?

What happens if the batteries run out during listening?

The sound will simply stop, maybe crackle a little bit first. There is no voltage spike or loud sound that will cause damage to your speakers or ears!

Battery Charger:

Can any battery charger be used?

No only the recommended one should be used . This is a smart charger specifically for LiFePO4 batteries. It has the correct connector to plug into the boxed Hiface & it automatically turns off when the batteries are fully charged. It is a single LiFePO4 charger so a maximum of 3.65V output. It has a low current output of 0.7amps so it won't burn out the internal wiring or switch of the Hiface box. Please check the label on the charger before use to ensure that it has an output voltage of 3.6V max. A mis-delivery of the wrong charger can cause damage to the batteries & Hiface - see above

When/How are the batteries charged?

When the Hiface unit is switched off the charger will automatically top-up the batteries until full & then switch itself to standby where a tiny trickle of charge is being applied. Charging the batteries regularly like this is not a problem for these batteries i.e. it won't shorten their lives. It is not recommended to leave the charger plugged into the box AND not connected at the wall as this will slowly drain the batteries.